REVISIO]Sr OF LISTROCHELUS — SAYLOR 69 



Thoracic disk usually glabrous, if slightly hairy then 



pygidial apex with a longitudiD9.1 impression 7 



7 (6). Dorsal surface shining, rarely elytra pruinose; serration of 



claws feeble to moderate; size 10-12 mm 8 



Dorsal surface and claws variable; size 13 mm. or more 10 



S (7). Form elongate, parallel; glabrous above or nearly so; 

 pygidium plane, very coarsely and densely punctate, 

 not impressed timlda (Horn) 



Form robust-oval; elytra and head (at times thorax also) 



hirsute 9 



9 (8). Pygidium plane, finely punctate, not at all impressed; 



elytra pruinose arizona, new species 



Pygidium polished, finely punctate, apical third with a 



deep longitudinal impression; elytra shining. _inacmurryi, new species 

 10 (7). Pygidium fiat or nearly so in basal three-fourths and usu- 

 ally densely pruinose, with at least the apical fifth always 

 raised slightly to strongly, and usually polished; dorsal 

 surface usually, or quite frequently, pruinose (note: the 

 Lower California mirafiora of the following couplet has 

 the basal half of the pygidium pruinose and slightly con- 

 vex, the apical half highly polished and evenly convex, 

 the center disk thus slightly f oveate) 11 



Basal half at least of pygidium always convex, usually 

 noticeabh^ so, if at all flattened then surface smooth, 

 highly polished, and without an apical raised portion 16 



11 (10). Pygidial apex very strongly gibbose (especially in lateral 



view) and surface very coarsely rugose, with dense, short 



hairs; claws serrate along a doublie margin scoparia (LeConte) 



Pygidial apex variable, not at all gibbose, usually smooth 



and polished, and densely pruinose 12 



12 (11). Pygidium strongly flattened and polished in apical third to 



half, with a definite longitudinal impression in polished 

 area; large intercalated tooth of tarsal claws always 

 nearly apical in position; inner hind tarsal claws without 



a larger intercalated tooth 13 



Pygidium not flattened apically, the polished raised area at 

 and before apex polished but transverse (fig. 8, m-o) and 

 without any impressed line, large tooth of claws median 

 in position; hind claws each with a strong median tooth 14 



13 (12). Pygidium with basal hairs short and inconspicuous; apical 



fourth very highly polished and sparsely, finely punctate, 



the latter area glabrous or nearly so pulcher (LineU) 



P3'gidium more densely pruinose and hairy in basal three- 

 fourths, hairs a little longer; apical fourth less highlj- 

 polished, more densely punctate, with short hairs. 



mucorea (LeConte) 



14 (12). Lateral thorax margins behind median dilation straight or 



nearly so; form robust and surface usually shining; 

 pygidium with raised smooth area in apical sixth only 



and this area not strongly V-shaped (fig. 8, m) disparilis (Horn) 



Thorax sinuate behind dilation; form elongate and sub- 

 parallel, surface usually moderately to densely pruinose; 



